We propose to continue our study of the sympathetic nervous actions of general anesthetics using newer agents and species not previously studied. In previous experiments (in cats), it was found that all general anesthetics could be divided with two classes based on their effect on cervical preganglionic sympathetic nervous activity. One class produced sympathetic activation while suppressing the barostatic reflexes; prior buffer nerve section blocked the sympathetic activation. The other class caused sympathetic inhibition, but preserved the barostatic reflexes. It was postulated that the first group of agents might act by depressing medullary depression neurones; the second group by depressing medullary pressor neurones. Our current plans are to extend this work to include other animal species besides the cat and to continue to study new anesthetic agents to see whether they all fall into one or the other of the two classes we defined. In addition, we plan to study the response in animals with brain stem sections in order to identify the site of anesthetic action.